Hermetically sealed overcurrent relay



P 1970 v. N. SHOFFA 3,528,045 HERMETICALLY SEALED OVERCURRENT RELAY I Filed Oct. 4. 1968 United States Patent 3,528,045 HERMETICALLY SEALED OVERCURRENT RELAY Vadim Nikolaevich Shoifa, Ul. 6a, kv. 11, Moscow, USSR. Filed Oct. 4, 1968, Ser. No. 765,169 Claims priority, application U.S.S.R., Oct. 5, 1967, 1,187,843 Int. Cl. H0lh 53/10 U.S. Cl. 335204 2 Claims ABSTRACT OF THE DISCLOSURE A hermetically sealed overcurrent relay comprises a hermetically sealed envelope through which extends a central conductor embraced by magnetically operated ferromagnetic contacts which are mounted on contact springs. A magnetic adjusting device in the form of two permanent magnets located outside the envelope and in the shape of half-rings, embraces the central conductor and the ferromagnetic contacts to produce magnetic fluxes which are superposed on the magnetic flux established in the ferromagnetic contacts by the current flowing in the central conductor.

The present invention relates to protective relays, and more specifically to hermetically-sealed magnetically operated overcurrent relays.

There is known a hermetically sealed overcurrent relay comprising an envelope which holds a cylindrical conductor embraced by two magnetically operated ferromagnetic contacts mounted on contact springs (see, for example U.S. Pat. No. 3,141,078, Class 200-87).

This hermetically sealed relay has the disadvantages that it does not provide for adjustment of the operatecurrent setting, while its envelope has to be sealed from four sides in manufacture.

An object of the present invention is to eliminate the above-mentioned disadvantages.

An object of the invention is to provide a hermetically sealed overcurrent relay having provisions for adjustment of the operate-current setting during service.

This object is achieved in a hermetically sealed overcurrent relay comprising an envelope holding a central conductor embraced by two magnetically operated contacts, wherein according to the invention, the operatecurrent setting can be adjusted by a magnetic adjusting device whose magnetic flux is superposed on the magnetic flux set up in the ferromagnetic contacts by the current flowing in the central conductor.

It is preferable to make the magnetic adjusting device from two permanent magnets placed outside the envelope and having the shape of half-rings which embrace the central conductor and the magnetically operated contacts.

The hermetically sealed relay embodied in accordance with the present invention accomplishes the object sought, that is, makes it possible to adjust the operate-current setting during service and also, with suitably located magnets, enhances the immunity of the open contacts of the relay to vibration and shock loads.

The invention will be best understood from the following description of a preferred embodiment when read in connection with the accompanying drawing, in which:

FIG. 1 is a cross-section of a hermetically sealed overcurrent relay according to the invention, and

ice

FIG. 2 is section taken on line II--H through the relay of FIG. 1.

Referring to FIGS. 1 and 2, therein is shown a relay comprising a glass envelope 1, a central conductor 2, ferromagnetic contacts 3 mounted on contact springs 4, and a magnetic adjusting device to adjust the operate-current setting of the relay, made up of two permanent magnets 5. The ferromagnetic contacts 3 have the shape of halfrings embracing the central conductor 1 and form, when open, an air-gap between their ends which serve as contact surfaces.

The permanent magnets 5 of the magnetic adjusting device are located outside the envelope 1 so that they embrace the half-ring contacts 3.

With the above arrangement of the relay components, the envelope has to be sealed from only two sides and not from four sides as is the case with conventional relays.

The relay disclosed herein operates as follows.

When a current starts flowing in the central conductor 2, the ferromagnetic contacts 3 are linked by a magnetic flux giving rise to electromagnetic forces which overcome the springs 4 and bring the contacts 3 together. When the current in the central conductor 2 approaches the operate value, the ferromagnetic contacts 3 close, thereby completing the external control circuit. As the current in the central conductor drops to the release value, the springs 4 force the contacts 3 to separate, and the control circuit is interrupted.

The operate-current setting is adjusted by shifting the permanent magnets 5 relative to the ferromagnetic contacts 3. The permanent magnets 5 are so arranged that the magnetic fluxes established by them in the ferromagnetic contacts 3 are bucking the magnetic flux set up in the contacts 3 by the current through the central conductor 2.

Apart from adjustment of the operate-current setting of the relay, the permanent magnets 5 improve the immunity of the open contacts 3 to vibration and shock loads when the central conductor 2 is de-energized.

What is claimed is:

1. A hermetically sealed overcurrent relay comprising: a hermetically sealed envelope; a central conductor passing through said envelope; magnetically operated ferromagnetic contacts embracing said central conductor; contact springs on which said ferromagnetic contacts are mounted; and a magnetic adjusting device externally on said envelope to adjust the operate-current setting of the relay, said magnetic adjusting device having a magnetic flux superposed on the magnetic flux established in said ferromagnetic contacts by the current flowing in said central conductor.

2. A hermetically sealed relay, as claimed in claim 1, in which the magnetic adjusting device comprises two permanent magnets located outside said envelope and having the shape of half-rings embracing said central conductor and said ferromagnetic contacts.

References Cited UNITED STATES PATENTS 3,141,078 7/1964 Wagar 335-196 3,254,173 5/1966 Prival 335-154 3,319,128 5/1967 Nilssen 335-153 X BERNARD A. GILHEANY, Primary Examiner R. N. ENVALL, ]R., Assistant Examiner 

